Mycoplasma Genitalium: Symptoms, Causes & Treatment

What Is Mycoplasma Genitalium?

Mycoplasma genitalium is one of the smallest self-replicating bacteria known to science. It was first identified in 1980 and is now recognized as a significant sexually transmitted infection (STI) that can cause urethritis in men and cervicitis in women, with potential serious complications if left untreated.

Mycoplasma genitalium, often abbreviated as M. genitalium or Mgen, is a bacterium that primarily infects the mucous membranes of the urogenital tract. Unlike many bacteria, M. genitalium lacks a cell wall, which makes it naturally resistant to certain antibiotics like penicillin that target bacterial cell walls. This unique characteristic contributes to the challenges in treating this infection.

The bacterium was discovered in 1980 at the London Hospital but was not recognized as a sexually transmitted pathogen until studies in the 1990s and 2000s established its role in causing genital tract infections. Today, it is considered one of the most important emerging sexually transmitted infections globally, affecting an estimated 1-2% of the general population.

M. genitalium primarily resides in the cells lining the urethra in both men and women, as well as in the cervix and vagina in women. The infection can persist for months or even years if untreated, even when no symptoms are present. This prolonged carriage without symptoms contributes significantly to its spread, as infected individuals may unknowingly transmit the bacteria to sexual partners.

How Is M. Genitalium Transmitted?

The primary route of transmission is through sexual contact when the mucous membranes of the genitals come into direct contact with each other. This occurs most commonly during vaginal intercourse, which is the most efficient mode of transmission. The bacteria can also be transmitted through anal intercourse, and there is ongoing research about transmission through oral sex.

Transmission can occur through contact with infected genital fluids, including semen and vaginal secretions. Unlike some other sexually transmitted infections, M. genitalium is not thought to survive well outside the body, so transmission through contaminated surfaces, toilet seats, or shared items like towels is considered highly unlikely.

The risk of transmission increases with certain factors, including having multiple sexual partners, not using barrier protection like condoms, and having concurrent infections with other sexually transmitted infections. Having another STI can create inflammation that makes it easier for M. genitalium to establish infection.

Who Is at Risk?

Anyone who is sexually active can contract M. genitalium, but certain groups face higher risk. Studies consistently show higher prevalence among younger sexually active adults, particularly those under 25 years of age. This is likely related to patterns of sexual behavior, including higher rates of partner change and lower rates of consistent condom use in younger age groups.

Individuals with multiple sexual partners, those who do not consistently use condoms, and people with a history of other sexually transmitted infections are at elevated risk. The infection is also more commonly detected among populations attending sexual health clinics, where prevalence rates can reach 15-20% among those presenting with symptoms of urethritis or cervicitis.

What Are the Symptoms of Mycoplasma Genitalium?

Symptoms of M. genitalium include painful urination (dysuria), abnormal discharge from the penis or vagina, lower abdominal pain, intermenstrual bleeding in women, and testicular pain in men. However, up to 70% of infected individuals may experience no symptoms at all.

One of the most challenging aspects of M. genitalium infection is that a significant proportion of infected individuals remain asymptomatic. Studies suggest that between 40-70% of women and 50-70% of men with the infection may not experience any noticeable symptoms. This high rate of asymptomatic carriage is a major factor in the ongoing spread of the infection, as people who feel well may unknowingly transmit the bacteria to sexual partners.

When symptoms do occur, they typically develop within 1-3 weeks after exposure, though the incubation period can be variable. The nature and severity of symptoms can vary considerably between individuals, and symptoms in men and women often differ based on the anatomical sites affected.

Symptoms in Men

In men, M. genitalium most commonly causes urethritis, an inflammation of the urethra. The symptoms of urethritis caused by M. genitalium can be similar to those caused by other pathogens like chlamydia or gonorrhea, making laboratory testing essential for accurate diagnosis.

The most common symptom reported by men is a burning or stinging sensation when urinating, known as dysuria. This discomfort is caused by inflammation of the urethral lining as urine passes through. The severity can range from mild discomfort to significant pain that affects quality of life.

Urethral discharge is another hallmark symptom, though it is often less pronounced than with gonococcal urethritis. The discharge is typically clear or slightly cloudy and may be most noticeable in the morning before urination. Some men describe a feeling of irritation or itching at the urethral opening even without visible discharge.

• Dysuria: Burning or stinging sensation during urination
• Urethral discharge: Clear to whitish discharge from the penis
• Urethral irritation: Itching or discomfort at the tip of the penis
• Testicular pain: Discomfort or pain in one or both testicles if epididymitis develops
• Rectal symptoms: Discomfort or discharge if rectal infection is present

Symptoms in Women

In women, M. genitalium can infect both the urethra and the cervix, and the infection may ascend to affect the upper reproductive tract. The symptoms in women are often more subtle than in men, which can lead to delayed diagnosis and treatment.

Cervicitis, inflammation of the cervix, is a common manifestation. This may cause changes in vaginal discharge, which might become more abundant, change in color or consistency, or develop an unusual odor. Women may also experience bleeding after sexual intercourse or between menstrual periods, known as intermenstrual bleeding.

Lower abdominal pain or pelvic discomfort can occur, particularly if the infection has spread to involve the upper reproductive tract. This pain may be constant or may worsen during sexual intercourse. Some women also experience painful urination similar to men, particularly if the urethra is involved.

• Abnormal vaginal discharge: Changes in amount, color, or consistency
• Intermenstrual bleeding: Bleeding between menstrual periods
• Post-coital bleeding: Bleeding after sexual intercourse
• Dysuria: Painful or burning urination
• Lower abdominal pain: Discomfort in the pelvic region
• Pain during intercourse: Discomfort during sexual activity

When Should You See a Doctor?

You should see a healthcare provider if you experience painful urination, unusual genital discharge, lower abdominal pain, bleeding between periods, or if you have had unprotected sex with a partner who may have an STI. Early testing and treatment prevent complications and further transmission.

Seeking medical attention promptly when you notice potential symptoms of a sexually transmitted infection is important for several reasons. Early diagnosis and treatment can prevent the infection from progressing to more serious complications, reduce the duration of symptoms, and prevent transmission to sexual partners.

You should consider getting tested for M. genitalium and other sexually transmitted infections if you experience any symptoms of urethritis or cervicitis, such as painful urination, unusual discharge, or pelvic pain. Even mild symptoms warrant evaluation, as M. genitalium symptoms are often less pronounced than those of other STIs like gonorrhea.

Testing is also recommended if you have had unprotected sexual contact with a partner who has been diagnosed with M. genitalium or another STI. Since many people with M. genitalium have no symptoms, partner notification and testing is an important part of controlling the spread of this infection.

It is worth noting that routine screening for M. genitalium in asymptomatic individuals is generally not recommended by most guidelines. This is partly because testing resources are limited in many settings, and because treating asymptomatic infection may contribute to antibiotic resistance without clear clinical benefit. However, this guidance may vary by region and clinical setting.

How Is Mycoplasma Genitalium Diagnosed?

M. genitalium is diagnosed using a nucleic acid amplification test (NAAT), which detects the bacteria's genetic material. For men, a urine sample is typically collected. For women, a vaginal swab is taken, which can often be self-collected. Results usually take 1-7 days depending on the laboratory.

The diagnosis of M. genitalium has historically been challenging because the bacterium grows extremely slowly in laboratory culture, making traditional culture-based methods impractical for routine clinical use. The development of molecular diagnostic tests, particularly nucleic acid amplification tests (NAATs), has revolutionized the ability to diagnose this infection accurately and relatively quickly.

NAATs work by detecting and amplifying small amounts of the bacterium's DNA or RNA present in clinical samples. These tests are highly sensitive, meaning they can detect infection even when bacterial numbers are low, and highly specific, meaning they are unlikely to produce false positive results. This makes them the gold standard for M. genitalium diagnosis.

Sample Collection

The type of sample collected depends on the patient's sex and the suspected site of infection. For men, a first-void urine sample is the standard specimen type. "First-void" means the first portion of urine passed when urinating, which contains the highest concentration of bacteria from the urethra. Men are typically asked not to urinate for at least one hour before providing the sample.

For women, vaginal swabs are the preferred sample type and often demonstrate higher sensitivity than urine samples. In many clinical settings, women are given the option to self-collect vaginal swabs, which studies have shown to be as accurate as clinician-collected samples while being preferred by many patients for comfort and convenience.

If there has been anal sex, rectal swabs may also be collected to test for rectal infection. Similarly, pharyngeal (throat) swabs might be considered in some cases, though M. genitalium pharyngeal infection appears to be uncommon and routine pharyngeal testing is not generally recommended.

Macrolide Resistance Testing

An increasingly important component of M. genitalium diagnosis is testing for macrolide resistance. Macrolide antibiotics, particularly azithromycin, have been first-line treatment options for M. genitalium, but resistance to these antibiotics has become widespread in many parts of the world, with resistance rates exceeding 50% in some populations.

Resistance testing identifies genetic mutations in the bacteria that confer resistance to macrolide antibiotics. This information is valuable because it allows healthcare providers to select the most appropriate antibiotic treatment from the outset, rather than prescribing a treatment that is unlikely to be effective. Many newer diagnostic tests include macrolide resistance detection as part of the standard panel.

When resistance testing is not available, or when initial treatment with azithromycin has failed, healthcare providers may need to use alternative antibiotics such as moxifloxacin based on clinical judgment and local resistance patterns.

How Is Mycoplasma Genitalium Treated?

M. genitalium is treated with antibiotics. The standard approach depends on macrolide resistance status: sensitive strains are typically treated with doxycycline followed by azithromycin, while resistant strains require moxifloxacin. Treatment courses range from 5 to 14 days, and you should abstain from sex during treatment.

The treatment of M. genitalium has become increasingly complex due to the emergence of antibiotic resistance. Unlike chlamydia and gonorrhea, for which highly effective single-dose treatments exist, M. genitalium often requires longer treatment courses with careful antibiotic selection based on resistance patterns.

Current treatment guidelines generally recommend a two-stage approach. The first stage typically involves a course of doxycycline for 7 days. Doxycycline alone rarely cures M. genitalium infection but reduces the bacterial load and may help subsequent treatment be more effective. The second stage involves azithromycin or moxifloxacin, depending on the resistance status of the infection.

For infections known or suspected to be macrolide-sensitive, azithromycin is given after doxycycline, typically in an extended course (such as 1 gram initially followed by 500mg daily for 2-4 additional days) rather than the standard 1 gram single dose used for chlamydia. This extended dosing appears to improve cure rates for M. genitalium.

Treatment During Pregnancy

Treatment of M. genitalium during pregnancy requires careful consideration of medication safety. Doxycycline and fluoroquinolones like moxifloxacin are generally contraindicated during pregnancy due to potential effects on fetal development. Azithromycin is considered safer during pregnancy and is typically the preferred option when treatment is necessary.

Pregnant women diagnosed with M. genitalium should discuss treatment options with their healthcare provider, who can weigh the risks of the infection against the potential risks of treatment. In some cases, treatment may be deferred until after delivery unless there is evidence of active disease causing complications.

Important Treatment Considerations

During antibiotic treatment, it is essential to abstain from sexual intercourse to prevent transmission to partners and to allow the treatment to work effectively. This abstinence should continue until both you and any treated partners have completed treatment and follow-up testing confirms the infection has cleared.

Sexual partners should be notified and offered testing and treatment, ideally at the same time as the index patient, to prevent reinfection. In many relationships, this means both partners being treated simultaneously and avoiding sex until both are confirmed cured.

What Complications Can M. Genitalium Cause?

Untreated M. genitalium can cause serious complications including pelvic inflammatory disease (PID) in women, which can lead to infertility, ectopic pregnancy, and chronic pelvic pain. In men, it can cause epididymitis. The infection may also increase susceptibility to HIV transmission.

While M. genitalium infection is often mild or asymptomatic, untreated infection can lead to significant complications, particularly in women. Understanding these potential complications underscores the importance of prompt diagnosis and effective treatment.

Complications in Women

The most serious complication in women is pelvic inflammatory disease (PID), which occurs when the infection ascends from the lower genital tract to involve the uterus, fallopian tubes, and surrounding structures. PID can cause acute illness with fever, severe pelvic pain, and tenderness, but it can also be subclinical with minimal symptoms while still causing damage to the reproductive organs.

The consequences of PID can be long-lasting and include increased risk of ectopic pregnancy (pregnancy outside the uterus, usually in a fallopian tube), chronic pelvic pain, and infertility due to scarring and damage to the fallopian tubes. Studies suggest that M. genitalium may cause or contribute to PID independently of other pathogens, though it is often found alongside other infections.

There is also growing evidence linking M. genitalium to adverse pregnancy outcomes, including preterm birth, spontaneous abortion, and low birth weight, though more research is needed to establish the strength of these associations.

Complications in Men

In men, the primary complication of untreated M. genitalium is epididymitis, inflammation of the epididymis (the coiled tube at the back of the testicle that stores and carries sperm). Epididymitis causes pain and swelling in the affected testicle and, if severe or recurrent, may potentially affect fertility.

Prostatitis (inflammation of the prostate gland) has also been associated with M. genitalium in some studies, though this relationship is less clearly established than for urethritis and epididymitis.

HIV and Other STI Interactions

Research has shown that genital tract inflammation caused by M. genitalium and other STIs can increase the risk of both acquiring and transmitting HIV. The inflammation increases the number of immune cells in the genital tract that HIV can infect and also disrupts the protective epithelial barrier. This is another important reason for prompt diagnosis and treatment of M. genitalium, particularly in populations at higher risk for HIV.

How Can You Prevent Mycoplasma Genitalium?

Prevention of M. genitalium involves consistent and correct use of condoms during vaginal and anal intercourse, reducing the number of sexual partners, and prompt testing and treatment when symptoms occur. Regular STI screening if you have multiple partners and open communication with partners also help prevent transmission.

Since M. genitalium is primarily transmitted through sexual contact, prevention strategies focus on reducing exposure and the likelihood of transmission during sexual activity. While no prevention method is 100% effective, combining multiple strategies provides the best protection.

Barrier Protection

Condoms, when used consistently and correctly, provide significant protection against M. genitalium transmission. Male (external) condoms should be applied before any genital contact and worn throughout intercourse. Female (internal) condoms are also effective and provide an alternative for those who cannot or prefer not to use external condoms.

For anal sex, condoms are similarly protective and should be used to prevent transmission. The effectiveness of barrier methods for oral sex is less well established for M. genitalium, but dental dams and condoms may provide some protection if pharyngeal transmission is a concern.

If sharing sex toys, using condoms on the toys and changing condoms between partners, or thoroughly cleaning toys between uses, can help prevent transmission.

Partner Communication and Testing

Open communication with sexual partners about STI status and testing is an important prevention strategy. Discussing recent testing, symptoms, and risk factors before engaging in sexual activity allows both partners to make informed decisions about protection measures.

If you have multiple sexual partners or your partner does, regular STI testing helps identify infections early, even before symptoms develop. While routine screening for M. genitalium is not currently recommended for asymptomatic individuals, testing should be considered if you have symptoms or known exposure.

When one partner is diagnosed with M. genitalium, notifying other recent sexual partners allows them to be tested and treated, breaking the chain of transmission. This partner notification is a crucial public health measure for controlling the spread of sexually transmitted infections.